I really wish that someone would produce a MANUALLY operated pre-loaded epinephrine syringe-- like the second dose in a twinject, if you see what I mean-- because I do worry so much about that spring-loaded mechanism. Sure, it makes self-administration much easier... and I understand that it makes administration easier in some ways for bystanders and laypersons...
but for a lot of people, it's also somewhat counter-intuitive to keep your fingers AWAY from the ends of the device-- the impulse is automatically to treat it like a retractable ball point pen. So why not have one that DOES work that way? grasp, place, and then--Click to administer, you know?
Not sure why that design has never gone anywhere. Without the big spring, the device could be a LOT smaller-- not much larger than an insulin syringe, in fact.